Bug: Agenda: Sorting TODOs (with tags) by effort does not work [8.3.6 (8.3.6-7-g4d7d52-elpaplus @ /home/luke/.emacs.d/elpa/org-plus-contrib-20161010/)]

[Luke <mideniko1234-org@yahoo.co.uk>]

I have the following custom agenda command set up:

===================================================
(setq org-agenda-custom-commands
      '(("x" "TODOs sorted by effort" todo "TODO"
     ((org-agenda-sorting-strategy
       '(effort-down))))))
===================================================

I would expect this to show me all my current TODOs, sorted by the
EFFORT property (in descending order).

I also have the following org-mode file:

===================================================
* TASKS
** TODO Task 1
   :PROPERTIES:
   :Effort:   0:02
   :END:
** TODO Task 2
   :PROPERTIES:
   :Effort:   0:10
   :END:
** TODO Task 3
   :PROPERTIES:
   :Effort:   0:30
   :END:
** TODO Task 4
   :PRyOPERTIES:
   :Effort:   0:05
   :END:
===================================================

When I execute the agenda command (M-x org-agenda RET x), then I get the
following result (as expected):

===================================================
Global list of TODO items of type: TODO
Available with `N r': (0)[ALL] (1)TODO (2)DONE
  gtd:        TODO Task 3
  gtd:        TODO Task 2
  gtd:        TODO Task 4
  gtd:        TODO Task 1
===================================================

*However*, then I add some tags to the TODO items, such as the
following:
 
===================================================
* TASKS
** TODO Task 1
   :PROPERTIES:
   :Effort:   0:02
   :END:
** TODO Task 2                :MY_TAG:
   :PROPERTIES:
   :Effort:   0:10
   :END:
** TODO Task 3
   :PROPERTIES:
   :Effort:   0:30
   :END:
** TODO Task 4                :@ONLINE:
   :PROPERTIES:
   :Effort:   0:05
   :END:
===================================================

Now when I execute the same agenda command I get the following:

===================================================
Global list of TODO items of type: TODO
Available with `N r': (0)[ALL] (1)TODO (2)DONE
  gtd:        TODO Task 2               :MY_TAG:
  gtd:        TODO Task 4               :@ONLINE:
  gtd:        TODO Task 3
  gtd:        TODO Task 1
===================================================


I wouldn't expect the order of items in the agenda to change. However,
even though I haven't specified any tag-based sorting strategy, it seemsas if the tags are still having some effect on the way that the agenda
is sorted.

I tried this same exercise with an older version of Org (built in to
Emacs 24.5.1) and that version didn't exhibit the same unexpected
behaviour.


Emacs  : GNU Emacs 24.5.1 (x86_64-pc-linux-gnu, GTK+ Version 3.18.9)
 of 2016-04-17 on lgw01-04, modified by Debian
Package: Org-mode version 8.3.6 (8.3.6-7-g4d7d52-elpaplus @ /home/luke/.emacs.d/elpa/org-plus-contrib-20161010/)

current state:
==============
(setq
 org-tab-first-hook '(org-hide-block-toggle-maybe org-babel-hide-result-toggle-maybe
              org-babel-header-arg-expand)
 org-speed-command-hook '(org-speed-command-default-hook org-babel-speed-command-hook)
 org-occur-hook '(org-first-headline-recenter)
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-confirm-shell-link-function 'yes-or-no-p
 org-agenda-custom-commands '(("x" "TODOs sorted by effort" todo "TODO"
                   ((org-agenda-sorting-strategy (quote (effort-down)))))
                  )
 org-after-todo-state-change-hook '(org-clock-out-if-current)
 org-src-mode-hook '(org-src-babel-configure-edit-buffer org-src-mode-configure-edit-buffer)
 org-agenda-before-write-hook '(org-agenda-add-entry-text)
 org-babel-pre-tangle-hook '(save-buffer)
 org-mode-hook '(#[nil "\300\301\302\303\304$\207"
           [org-add-hook change-major-mode-hook org-show-block-all append local] 5]
         #[nil "\300\301\302\303\304$\207"
           [org-add-hook change-major-mode-hook org-babel-show-result-all append local] 5]
         org-babel-result-hide-spec org-babel-hide-all-hashes org-eldoc-load)
 org-archive-hook '(org-attach-archive-delete-maybe)
 org-ctrl-c-ctrl-c-hook '(org-babel-hash-at-point org-babel-execute-safely-maybe)
 org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers org-cycle-show-empty-lines
          org-optimize-window-after-visibility-change)
 org-confirm-elisp-link-function 'yes-or-no-p
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 org-agenda-files '("~/gtd/gtd.org")
 org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
 )